Such prostheses have already formed the subject matter of several prior inventions, for example the one described in French Application FR 2 446 631.
This prosthesis is essentially constituted by a biventricular one-piece assembly which comprises a tight shell implantable in the pericardiac cavity, made of a material which is compatible and non-toxic with respect to the surrounding tissues and presenting a specific geometry, which reproduces the configuration of the natural heart in two right and left ventricular chambers.
This prosthesis contains: 1) a device for pumping of blood essentially constituted by two membranes, of which one defining the right ventricle works in elongation and of which the second defining the left ventricle works in deformation; 2) valves mounted in the inlet and outlet orifices; 3) means for activating the above-mentioned pumping membranes which furnish them with supply pressures substantially equivalent to the physiological values; 4) means for regulating the cardiac output as a function, on the one hand, of the filling pressure and, on the other hand, of the aortic pressure.
However, with such a prosthesis, a) the activation and regulation means controlling the pumping membranes is not mounted directly on the prosthesis, which increases the volume of the whole and complicates implantation thereof; b) the activation means is unique for the two membranes, rendering the problems of regulation more delicate and random; c) the prosthesis is not rendered biocompatable; and d) it does not allow replacement of certain of its functional elements, which operation may prove necessary in the event of a failure or wear and which it is desirable to be able to effect without changing the whole prosthesis.
U.S. Pat. No. 4,397,049 (ROBINSON et al) describes a cardiac prosthesis comprising two ventricular chambers, each being provided with two orifices, one serving for the inlet of the blood, the other for ejection, and with an activation device constituted by an electro-pneumatic member. However, each chamber presents only one flexible membrane.
Patent FR 2 370 184 (NIKKIOS) describes a pulsatile pump for blood circulation comprising a driving pouch provided with an inlet orifice and with a delivery orifice provided with valves, said pouch being in contact with a pressure transmission chamber defined by a diaphragm and compressed by a piston to generate a movement corresponding to the physiological pulsation. However, this pump is not implantable.
U.S Pat. No. 3,478,695 (GORANSON et al) describes a heart pump with a chamber comprising at least two deformable enclosures, the first being connected to a source of pressure and the other being connected to the heart; pressurization of the first having for its effect to compress the second directly upon contact and thus to provoke delivery of a determined volume of blood towards the heart. The bladder inflates under the effect of the pressurization of the first enclosure and makes it possible to avoid, after delivery, the second enclosure resuming its initial shape too rapidly by suddenly sucking a fresh volume of blood.
However, this pump cannot be mounted directly either on the heart or on any prosthesis.